This invention relates to a friction clutch wrench for use in applying torsion to objects of a predefined range of size and cross-sectional shape. The jaws open and then close to engage an object within the operating ranges of the wrench. Once the jaws are engaged on the work, the friction clutch gripping mechanism in the jaws allows unidirectional torsion to be applied in a stepless ratchet technique. The preferred embodiment herein will operate equally well on conventional threaded hexagonal fasteners, or on the outside surfaces of cylindrical objects such as sockets or pipes. The effective operation of this invention is not limited to these cross-sectional shapes, however. This design will operate satisfactorily on any object whose cross-sectional size and shape will engage properly on the friction clutch mechanism provided in the jaws.
The basic friction clutch ratchet mechanism in the jaws was disclosed as early as 1923, in U.S. Pat. No. 1,412,688 issued to hymn and Hopkins. Until now, however, improvements on this technology have been limited to closed-ended devices, where the wrench is required either to be slipped over one end of the object to be turned, or to be connected axially to one end of the object by a means such as a square drive. See, e.g., Anaha, U.S. Pat. No. 2,896,488; Chern, U.S. Pat. No. 4,987,802; Headen, U.S. Pat. No. 4,603,606. Previous friction clutch ratchet mechanisms in open-ended wrenches have provided localized grip only, and have provided minimal flexibility in terms of the size of the fastener or component that the wrench will operate on. See, e.g., Crittenden, U.S. Pat. No. 2,730,000; Hertelendy, U.S. Pat. No. 3,927,582. The locking grip pliers mechanism used to close and lock the jaws on the present invention is well known in the art.
The present invention thus improves on the prior art to produce a wrench design that is apparently unknown in the art. Much like an open-ended wrench, its open jaws provide access to fasteners and components from the side. Once closed and locked over the work, however, the wrench assumes the strength and rigidity of a closed-ended wrench while providing an all-round stepless ratchet grip.